Communication system networks are known to comprise a plurality of communication systems and a central controller. Each of the communication systems comprises a plurality of communication units, a limited number of communication resources that are transceived via a limited number of repeaters, and a communication resource allocator that allocates the communication resources among the plurality of communication units. The communication units, which may be mobile radios, portable radios, and/or portable radio/telephones, are typically arranged in to communication groups and are generally located throughout the communication system network. Of the communication resources, which may be TDM slot locations, frequency carriers, pair of frequency carriers, or any other RF transmission means, one is selected to function as a control channel. The control channel transceives operational information between the communication units and the central controller via the communication resource allocators.
As is known, a communication unit may establish a communication with other communication units within the communication system network by transmitting an inbound signalling word (ISW) to the central controller via the communication resource allocator of the communication system that the communication unit is located in. Upon receiving the request, the central controller processes it and, if the request is valid, the central controller allocates a communication resource in each of the communication systems that have a communication unit of the targeted talk group in it. The communication systems, which may also be communication sites, are coupled to and controlled by the central controller. If a communication system, or site, loses contact with the central controller, the communication system, or site, operates as an independent communication system but only for communication units that are located within its coverage area.
In addition to the above, a communication system network may further comprise operator stations, or consoles. An operator station allows a dispatcher, for example, to monitor the activity of particular communication groups. The operator may be allowed to select which communication groups its monitoring or that may be predetermined by a system manager. In the case where the operator station allows the operator to select which communication groups that it will monitor, the selection of group services is performed over the entire network. Thus, for example, when the dispatcher desires to place a call to a particular communication group to respond to an emergency, the central controller would allocate a communication resource in each of the communication systems for that particular call. This is inefficient when the particular system service to be performed is generally geared for a localized area. For example, the group service may be an emergency call wherein police units within a two or three mile radius of where the emergency is occurring would physically be able to respond and yet with present systems, communication units throughout the entire network would hear the emergency even though they may be up to 20 or 30 miles away.
In addition to emergency conditions, group services may also include status updates, general communications and other known services that communication system networks provide. Therefore, a need exists for a method that allows an operator of an operator station to individually select which communication sites, or systems, the operator desires to perform the selected group service in.